Hi Helmut,
I agree with all of Philipp's and Alex's comments; one minor thing I'd
mention...
> ***If*** 1=yes and 2=satisfactory, and if there are no format problems,
> then off the top of my head I can’t see much of a problem (as shocking
> as it sounds). Knowing you, you will of course check for any systematic
> differences between the two preprocessing pathways… and I hope the two
> groups don’t correspond to patients versus controls etc.
Maybe it would be worth including a covariate to indicate processing
pathway? Rather like the suggestion here
http://en.wikibooks.org/wiki/SPM-VBM#Data_from_different_scanners
Then your results will be (correctly) less significant the more
correlated the processing pathway indicator variable is to the effect
of interest.
Best,
Ged
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